Monthly Archives: October 2020

How the ongoing global pandemic drives Legionella concerns

Even before COVID-19, Legionella had the distinction of being one of the leading water- borne disease agents in the USA, with reported cases growing more than 5-fold from 2000-2017 (CDC). But now, as COVID-19 and stagnant water due to building closures collide, the threat increases.

What is Legionella?

Legionella bacteria occur naturally in warm, freshwater environments, like lakes and streams. They become problematic to health when they grow in plumbing systems, particularly where biofilm has developed on pipe walls, and then spread as water is distributed throughout the building. To cause infection, Legionella must be aspirated making showerheads, water fountains, cooling towers, and, less commonly, taps and drinking fountains points of contamination. In high risk populations, Legionella infection can cause a serious type of pneumonia. The simplest way to prevent infections is to keep Legionella out of building water systems.

Ultraviolet (UV) disinfection is a proven solution for preventing Legionella contamination of building water systems, and is suitable for:

  • Hospitals and healthcare facilities
  • Schools
  • Office and commercial buildings
  • Homes

We're here to help. Ask us what kind of UV system is best for your needs.

UV can be applied at the point-of-entry as a complementary disinfection barrier for the whole building or at point-of-use for high risk areas within a plumbing system. Different species of Legionella require different UV dose levels for inactivation. However, in general, required doses are low and well within the operating parameters of our range of UV systems.

Legionella Species 3-log 4-log 5-log
Legionella Bozemanii 3.5 mJ/cm2 4.7 mJ/cm2 5.83 mJ/cm2
Legionella dumoffi 5.5 mJ/cm2 7.33 mJ/cm2 9.17 mJ/cm2
Legionella gormanii 4.9 mJ/cm2 6.55 mJ/cm2 8.17 mJ/cm2
Legionella micdadei 3.1 mJ/cm2 4.13 mJ/cm2 5.17 mJ/cm2
Legionella longbeachae
(found in potting soil)
2.9 mJ/cm2
Legionella pneumophila
(legionnaires disease)
3.8 mJ/cm2 5.1 mJ/cm2 6.33 mJ/cm2
Legionella interrogans
(infectious jaundice)
6.0 mJ/cm2

Controlling Legionella

Routine Legionella testing is not common in the operation and maintenance of many building water systems, with the exception of hospitals and healthcare facilities. But, given the extensive shutdowns and low-level use and occupancy of so many buildings, including schools and offices, testing is strongly encouraged. Where Legionella is detected, the corrective actions include disinfection (thermal or hyper-chlorination) and flushing, followed by repeat testing. UV disinfection can then be employed to avoid re-inoculation of the plumbing system.


Find Out More


Let us help you understand how to leverage UV to minimize stagnant water risks going forward.

Simply fill out the form below.

UV water treatment for “brain-eating” amoeba (N. fowleri)

The role of any public water treatment facility, be it city, town, or municipality, is to deliver water to your home that is fit for drinking. Point-of-entry water treatment in your home, like an ultraviolet (UV) disinfection system, provides an additional barrier to ensure the quality of water at every tap in the home and for every purpose.

Why every tap matters

Naegleria fowleri is an amoeba, or single-celled living organism which causes a serious brain infection called primary amebic meningoencephalitis (PAM) that, while very rare, is often fatal. Consuming water contaminated with N. fowleri is not an issue as it is destroyed by stomach acid. Instead, it enters the body through the nose where it then migrates to the brain via the olfactory nerve. Since the organism is normally found in warm waters, infections are most often associated with swimming/diving in recreational waters – but not always! Cases have been linked to contaminated tap water entering the nose during nasal rinsing such as with a neti pot. Accidental exposures to N. fowleri, especially involving children, are also possible where the head is immersed in contaminated water or contaminated water goes up the nose during:

  • Bathing or showering;
  • Swimming in “kiddie pools” filled with tap water;
  • Unsupervised play with outdoor hose bibs or sprinklers.

Where does N. fowleri occur?

Incidents of N. fowleri being detected in North American water distribution systems have only occurred in the warm climates of Louisiana (2013) and Texas (2020). However, cases of PAM have been reported in a wider geography including 15 southern states, as well as Minnesota, Kansas, and Indiana. No water distribution system is immune to pipe breaks or pressure fluctuations that could allow an environmental contaminant like N. fowleri access. If the water temperature is warm and disinfectant levels are low, it could colonize and put water users at risk.

How to treat for Naegleria fowleri

In implementing water treatment for N. fowleri the goal should be a 4-log reduction of the cysts. UV disinfection is a chemical-free approach that will not alter the taste or odour of the water. Trojan Technologies provides a range of UV systems to meet the needs of homes, businesses or public water systems. Learn more about our brands here.

Get a quote

Fill out the form below to get a quote.